The present invention relates to apparatus for the manufacture of wire net fabric made from at least one straight supplied endless wire. The apparatus has a stationary twisting worm screw, which includes a helical guide groove for each supplied wire for holding said wires, whereby two grooves are displaced axially relative to each other by the amount of the width of a single weave. The invention apparatus also has a flat coiling mandrel which cooperates with the twisting worm screw and which receives the flat-drawn wire coil formed from each wire and leads it axially to the entrance of a circular twisting tube, which has a slot along one axis-parallel cover line, through which slot the projecting bent loops of the securable last coil of the finished fabric section engage in the tube, into which loops the coiling mandrel threads the next coil as it leaves said mandrel, the beginning of which next coil can be determined by means of a cutting device, and having a drive means to rotate the coiling mandrel about its longitudinal axis, which is aligned with the tube axis.
In known devices of the above-described type, such as that disclosed in DE-PS No. 1 160 396 to Wafios, the mandrel drive consists of a motor portion, a transmission portion and a coupling portion, with which a braking portion is associated, so that the coiling mandrel, the so-called weaving blade, can be brought to a stop as rapidly as possible during uncoupling. Because this stopping is dependent upon chance and uncertainties, it does not occur with precise positioning. Therefore, at an additional operating expense, which presupposes a corresponding additional structural expense, the weaving blade must be brought into its original rotational position each time, before the cutting device separates the preceeding wire coil located in the weaving tube from the subsequent wire coil sitting on the weaving blade. Without that positioning, the cutting point would not be defined on the coil wire and it could then lead to operational disruptions as the next coil is threaded into the preceeding weaving batch.
In prior art devices of the type described hereinbefore, the rotational speed of the weaving blade can be changed step-wise by switching the transmission portion. During such a switch the electro-mechanically controlled uncoupling-braking process must be adapted to the new rotational speed, for example by displacing the switch lug of a contactless switch. Furthermore, the rotational speed is limited to the speed at which the next coil can be smoothly threaded into the preceeding coil, namely over the entire width of the fabric. Disruptions are possible not only at the beginning, where the subsequent coil is introduced into the preceeding coil, but also toward the end of the threading operation, where, due to the increasing width of the fabric, increasing difficulties are encountered as a result of the fact that the friction of the bent loops of the flattened wire coil on the inner wall of the weaving tube, which is dependent on the coil length, coil pitch and wire thickness, leads to a torsion in the rotating coil in the weaving tube. That results in a change in the coil pitch, which, in turn, causes the beginning of the coil to miss the rear-most openings in the finished section of fabric. In the case of an addition of two intertwined wire coils to the woven edge by threading one of the two coils into the last coil of the finished fabric section, it has also been noted that at too high a rotational speed of the weaving blade, the indirectly added coil is improperly threaded into the fabric edge with the directly added coil, so that, at least the uniform structure of the fabric is disturbed. However, if the rotational speed of the weaving blade is necessarily held so low that the aforementioned disruptions do not occur, the productivity of the device is only moderate.